Hydrofluorocarbon (HFC) refrigerants such as 134a have long been used to provide cooling using vapor compression cycles. However, these and many other commonly used refrigerants have deleterious environmental effects. Carbon dioxide, on the other hand, provides a much more environmentally friendly option for vapor compression cooling and heating. However, the pressures required to incorporate CO2 in existing vapor compression systems, and the inefficiency of these systems have slowed the transition from HFC refrigerant based systems to CO2 based vapor compression cooling systems. Accordingly, there remains a need for environmentally friendly and efficient cooling systems. Embodiments disclosed herein are designed to address these needs, and provide additional benefits to the heating and cooling industry.